Method of manufacturing a laminated tubular article having a matte finish surface



Nov. 17, 1970 J. H. CONNOR 3,540,9fi

METHOD OF MANUFACTURING A INATED TU JAR ARTICLE HAVING A MATTE IS URFOriginal Filed Feb. 1964 INVENTOR.

United States Patent 3,540,959 METHOD OF MANUFACTURING A LAMINATEDTUBULAR ARTICLE HAVING A MATTE FINISH SURFACE John Houghton Connor,Chester, N.J., assignor to American Can Company, New York, N.Y., acorporation of New Jersey Continuation of application Ser. No. 346,686,Feb. 24, 1964. This application Mar. 14, 1969, Ser. No. 808,377 Int. Cl.B29d 23/10 US. Cl. 156-203 2 Claims ABSTRACT OF THE DISCLOSURE A methodof preparing the surface of a sheet of thermoplastic material to reduceits area of contact and consequent frictional resistance with thesurface of a forming tool over which the sheet is shaped in themanufacture of containers. The inner surface of the thermoplastic sheet,which is the surface which makes direct contact with the forming toolduring the container manufacturing operation, is given a coarse or mattefinish, characterized by closely spaced minute irregularities on theorder of about 5.0 to 25.0 micro inches in height and depth, measured onthe basis of an arithmetic average. Preferably, the finish is impressedon the thermoplastic material during its formation in an extrusionoperation and while it is still thermally soft by passing it over achill roll having a matte finish surface of the desired coarseness.

This application is a continuation of an earlier filed application, Ser.No. 346,686, filed Feb. 24, 1964, now abandoned.

- This invention relates to the manufacture of tubing, and isparticularly directed to improvements in the art of making continuoustubing from laminated web stock by the process of progressively shapingthe web about an elongate forming member as the web is fedlongitudinally onto the member.

Various techniques are known for fabricating tubing from flat stock. Onetype of continuous operation is to shape an endless web of selectedmaterial into tubular configuration by passing the web over an elongateforming horn or mandrel while progressively folding the web about themandrel and seaming its longitudinal edges together. This technique hasbeen used in the manufacture of tubing of many types of materials,including metals, papers, plastics and various laminations of thesematerials, and has found particular utility in the fabrication oftubular container bodies of laminated stock. This enables theaccomplishment of certain preliminary operations, such as labeling,coating, the application of barrier films, etc., while the stock isstill in the fiat and has the advantages of easier and more economicaloperation.

One drawback of forming tubing in this manner, however, is in the factthat, in folding and shaping the Web over the mandrel, there isconsiderable frictional engagement between the mandrel and the innersurface of the web. This is accentuated by drawing the Web intorelatively tight encirclement of the mandrel to ensure accurate sizingof the tubing as it is formed, and is particularly severe where theinner surface of the web, or that surface which actually engages themandrel, has a high coefficient of friction or other surfacecharacteristics which promote sticking. The gloss surface finish ofpolyethylene film, for example, has been found to be especiallysusceptible to seizure or sticking to the mandrel surface. In suchinstances, it is necessary to-increase the feed tension on the web as itis formed to overcome this frictional resistance and it will beappreciated that there is a limit to the amount of tension that can beapplied before either slippage between the web and its feed mechanism orsevere damage and breakage of the web occurs.

The primary object of my invention, therefore, is to overcome theseproblems in forming continuous tubing from flat web stock by reducingthe frictional resistance of the forming tool to the moving Web.

Another object of this invention is the provision of an improvement inthe art of forming continuous tubing wherein the frictional contactbetween the web as it is formed and the forming tool is substantiallyreduced.

Still another object of this invention is to provide an improved methodof forming continuous tubing by conditioning the inner surface of thetubing preparatory to shaping it on an elongate forming tool to reduceits frictional contact with the tool during the shaping operation.

The manner in which these objects are achieved will be made clear fromthe following description which, taken in connection with theaccompanying drawing and appended claims, disloses a preferredembodiment of my invention.

Referring to the drawing:

FIG. 1 is a perspective view of an illustrative form of apparatus forthe practice of my novel method;

FIG. 2 is a perspective view of a shaping operation showing the step offorming continuous tubing from an endless web after it has beenconditioned according to my invention; and

FIG. 3 is an enlarged fragmentary sectional view taken substantiallyalong lines 3-3 of FIG. 2.

As illustrative of the type of operation where my invention may bepracticed, I have illustrated in FIG. 1 a typical apparatus forfabricating laminated web stock. For purposes of illustration and notlimitation, the web W is a three ply structure comprising a first ply 10of thermoplastic material, an intermediate barrier ply 11 of imperviousmaterial, such as metallic foil, and a second thermoplastic ply 12. Thethermoplastic plies 10 and 12 may be of like or dissimilar material,depending on the specific characteristics desired, examples of which arepolyethylene, polyvinyl chloride, polyvinylidene chloride,polypropylene, etc. The final web may contain additional plies orlayers, examples of which are special papers, adhesive resins, etc., andin the case where the web is used in the manufacture of packingcontainers it normally is printed in the fiat with advertising anddecorative indicia. The indicia may be applied to the outer surface ofply 10 or between the barrier ply 11 and the ply 10 if the latter is atranslucent thermoplastic. These variations in the structural makeup ofweb W play no part in my instant invention but are illustrative of thedifferent forms which the laminated web may take to satisfy differentspecific uses.

The instant invention resides in the manner of preparing or conditioningthe final thermoplastic ply 12 which makes up web W so that itsfrictional engagement with the forming tool on which the web is to beshaped into tubular configuration is substantially reduced. Asillustrated in FIG. 1, the final ply may be applied to previously bondedplies 10 and 11 in the form of an extruded film which emerges in aheated state from an elongate nozzle of an extruder unit 13. The heatedfilm first passes between the nip of a pair of rollers 14 and 15 andthen is fed along with plies 10 and 11 between the nip of another pairof rollers 16 and 17, the latter serving to press and bond the ply 12 tothe upper surface of ply 11 to complete the forming of web W. The web isthen cut into individual narrow webs of desired width by a cuttingdevice 18 and finally wound into individual coils or rolls, illustratedas W1, W2, W3, which rolls are later used in forming continuous tubingas hereinafter described. If desired, roller 15 may be chilled tofacilitate the cooling and partial setting of thermoplastic ply 12. Thedesired roller temperature may be maintained by any suitable means, anexample being by circulating a refrigerant within the roller throughinlet and outlet conduits 19, 20 which may be appropriately connected tothe interior of the roller through its mounting shaft.

The surface S of roller 15 has special and unique characteristics whichenable the conditioning or preparation of the surface S of the ply 12 torender this surface, as the inner surface of the tubing to be formed,less frictionally resistant to the forming tool over which the web isshaped in the forming operation. The roller surface S may be describedas having a matte finish characterized by closely spaced minuteirregularities in the form of random projections and depressions.

An example of such a surface is that produced on a roller having aninitially smooth, thin chromium layer plated to the outer surface of thebase metal of the roller, which chromium layer has been subjected toblasting with a fine grit, such as alumina, silicon carbide or the like,which ranges in size from about 50 to 150 mesh. The blasting of theroller surface may be carried out in any one of several ways, specificexamples of which are given in U.S. Pat. No. 3,063,763 to W. J.Zubrisky. As explained in said patent, the variations inherent in gritblasting renders it impossible to give exact dimensions to the randomprojections and depressions produced thereby, but that measurements witha profilometer enable the determination of a range of the depth of theirregularities on the basis of an arithmetic average. For the purposesof the instant invention, the terms matte finish and minute surfaceirregularities as used herein are intended to refer to a surfacecondition characterized by randomly spaced While the example referred toabove is concerned with a chromium plated roller grit blasted in thedesignated manner, it is to be understood that I contemplate in thepractice of my invention the use of rollers having surfaces hardened bymeans other than chromium plating, examples being case hardening orplating with other metals known to have high hardness characteristics.

As the thermoplastic ply 12 passes between the nip of rollers 14 and 15,the special surface S on rollers 15 prints or impresses on the uppersurface S of the thermoplastic ply a corresponding pattern havingsubstantially identical surface irregularities in the form of randomlyspaced minute projections s and depressions s (see FIG. 3). In passingover roller 15, the web is chilled to a semisolid or somewhat tackystate, a condition most suitable for receiving a full and permanentimpression. The arithmetic average depth of the depressions s or heightof the projections s is substantially equal to those on the rollersurface S, ranging from about 5.0 to about 25.0 microinches. Theprojections s are of tooth-like configuration having sharp or pointedextremities and present a somewhat uniform or even contact surface ofsubstantially reduced contact area by reason of the small pointedextremities being separated by the intervening depressions s Theimportance of this reduced contact area on the surface of ply 12,corresponding to the interior surface of the tubing to be formed from astrip of web W, is best appreciated by reference to FIG. 2 whichillustrates a typical "apparatus for forming tubing continuously fromexterior surface of the web strip to move it continuously onto themandrel and through the shaping block.

During its travel, the strip W1, is progressively folded around themandrel in tight encirclement and its opposite longitudinal edges areoverlapped and joined together as a lap seam L by a heated pressureroller 24 or equivalent seaming member. To ensure accurate sizing of thetubing as it is formed and to provide suflicient reactant surfacebeneath the lapped edges to accomplish the seaming operation, it isnecessary that the tubing tightly encircle the mandrel 22 for asubstantial distance. However, the frictional contact between the tubingand this length of the mandrel, which tends to resist the movement ofthe tube and cause possible slippage and/or seizing, is reduced to aminimum by reason of the presence of projections s and depressions s onthe inner surface of the tubing, as seen in FIG. 3. The only frictionalcontact between the tubing and mandrel is that represented by the totalof the small pointed extremities of tooth-like projections s this beingonly a fraction of the total surface area which could make frictionalcontact with the mandrel if not conditioned in the above describedmanner.

Where the tubing is to be used in discrete lengths, as for example, inthe manufacture of container bodies, it may be cut into desired lengthsby conventional automatic cutting equipment as it leaves the mandrel.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and it will beapparent that various changes may be made in the steps of the methoddescribed and their order of accomplishment without departing from thespirit and scope of the invention or sacrificing all of its materialadavntages, the method hereinbefore described being merely a preferredembodiment thereof.

I claim: 1. A method of making tubular articles of laminated materialscomprising the steps of:

forming a base layer of at least one selected material; separatelyextruding a thermoplastic material to form a heated thermoplastic secondlayer;

passing the heated, thermoplastic second layer between the nip of tworollers, one of which rollers is a chilled roller having a surfacehardened, matte finish thereon characterized by closely spaced, minutedepressions of an arithmetic average depth of about 5.0 to 25.0microinches, to produce on a surface of the thermoplastic second layer amultitude of closely spaced, minute projections,

placing the other surface of the thermoplastic second layer in contact'with the base layer, applying pres sure to said layers to form alaminated web,

and shaping the 'web over an elongate forming tool by moving the weblongitudinally of and progressively folding it about the forming toolwith the thermoplastic second layer in intimate sliding contacttherewith to thereby form the web into a tubular configuration with aminimum of frictional resistance between the web and the forming tool.

2. A method of making tubular articles of laminated materials comprisingthe steps of:

forming a base layer of at least one selected material;

separately extruding a thermoplastic material to form a heatedthermoplastic second layer; placing a surface of the thermoplasticsecond layer in contact with a surface of the base layer; applyingpressure to said layers to form a laminated passing said laminated Webbetween the nip of two rollers, one of which rollers is a chilled rollerhaving a surface hardened, matte finish thereon characterized by closelyspaced, minute depressions of an arithmetic average depth of about 5.0to 25.0 microinches, to produce on a surface of the thermoplastic secondlayer a multitude of closely spaced, minute projections; and

5 6 shaping the web over an elongate forming tool by mov- 3,195,4277/1965 Adams l56218 X ing the Web longitudinally of and progressivelyfold- 3,195,428 7/ 1965 Tuma 156200 X ing it about the forming tool Withthe thermoplastic 3,411,542 11/1968 Walsh et a1. 156-218 X second layerin intimate sliding contact therewith to thereby form the web into atubular configuration FOREIGN PATENTS With a minimum of frictionalresistance between the 5 142831953 1/1962 Franceb d th f t 1. We an eCARL D. QUARFORTH, Primary Examiner References Cited S. J. LECHERT JR.,Assistant Examiner UNITED STATES PATENTS 10 2,799,896 7/1957 Grow 6128.118-47 2,941,570 6/1960 Plym 156-203 156-209, 218, 219, 220, 222, 244,306; 161-464, 178,

2,578,664 12/1951 Beery et al. 156-200X 293

